In a motor device in which rotation of a motor is transmitted through a worm gear, a structure has been proposed that a compression coil spring is disposed between a rotation shaft and the worm gear (see, Patent Literatures 1 and 2). More specifically, in Patent Literature 1, a structure has been proposed that a compression coil spring is provided around a shaft which is located between an end part on a motor main body side of a worm gear and a connecting means connected with a motor shaft. In Patent Literature 2, a structure has been proposed that a recessed part is formed on an end face located on a motor main body side of a worm gear and a compression coil spring is provided between a bottom part of the recessed part and a motor shaft. The recessed part is formed shallow so as not to reach to a portion whose outer peripheral face is formed with a spiral groove.